# -*- coding: UTF-8 -*-
from typing import List, Dict
from leetcode_helper import TestcaseHelper, SolutionBase


class Solution(SolutionBase):
    # 解题的方法，命名和Leetcode的保持一致即可
    def subarraySumForce(self, nums: List[int], k: int) -> int:
        length = len(nums)
        count = 0
        for left in range(length):
            sums = 0 # sums 代表，left..right的元素和
            for right in range(left, length):
                sums += nums[right]
                if sums == k:
                    count += 1

        return count

    def subarraySumPresum(self, nums: List[int], k: int) -> int:
        length = len(nums)
        count = 0
        presum_array = [0] * (length + 1)   # 前缀和数组，presum_array[i]代表前i个元素的和，总长度为length + 1

        for i in range(0, length):
            presum_array[i+1] = presum_array[i] + nums[i]

        for i in range(length):
            for j in range(i, length):
                if presum_array[j + 1] - presum_array[i] == k:
                    count += 1

        return count

    def subarraySum(self, nums: List[int], k: int) -> int:
        length = len(nums)
        count = 0
        pre = 0

        dict: Dict[int, int] = {0: 1}

        for i in range(0, length):
            pre = pre + nums[i]     # 求P[i]
            if dict.get(pre - k, None):
                count += dict.get(pre - k)
            dict[pre] = dict.get(pre, 0) + 1

        return count


if __name__ == '__main__':
    solution = Solution()

    # 按照leetcode的题目说明，将基本的test case填入
    # 每条case的最后一个元素是正确的结果，即期待的结果
    # 使用元组来保存输入的数据，期待的结果
    testcases = [
        ([1, 1, 1], 2, 2),
        ([1, 2, 3], 3, 2)
    ]

    for case_item in testcases:
        # 获取测试用的case和期待的执行结果
        input1 = case_item[0]
        input2 = case_item[1]
        expect = case_item[len(case_item) - 1]
        exec_result = solution.subarraySum(input1, input2)

        # 判断执行结果，输出提示信息
        check_result = solution.check_result(expect, exec_result)
        TestcaseHelper.print_case(check_result, case_item, exec_result)

